Particulate carriers have been used with adsorbed or entrapped antigens in attempts to elicit adequate immune responses. Such carriers present multiple copies of a selected antigen to the immune system and promote trapping and retention of antigens in local lymph nodes. The particles can be phagocytosed by macrophages and can enhance antigen presentation through cytokine release.
For example, commonly owned International patent application WO 98/33487 (PCT/US98/01738) and co-pending U.S. patent application Ser. No. 09/015,652, filed Jan. 29, 1998, describe the use of antigen-adsorbed and antigen-encapsulated microparticles to stimulate immunological responses, including cell-mediated immunological responses, as well as methods of making the microparticles. Polymers used to form the microparticles include poly(lactide) and poly(lactide-co-glycolide), also referred to herein as “PLG”.
Commonly owned International patent application WO 00/06123 (PCT/US99/17308) and co-pending U.S. patent application Ser. No. 09/715,902 disclose methods of making microparticles having adsorbed macromolecules, including polynucleotides and polypeptide antigens. The microparticles comprise, for example, a polymer such as a poly(alpha-hydroxy acid) (e.g., PLG, a polyhydroxy butyric acid, a polycaprolactone, a polyorthoester, a polyanhydride, and the like) and are formed using, for example, cationic, anionic or nonionic detergents. Microparticles containing anionic detergents, such as PLG microparticles with sodium dodecyl sulfate (SDS), are proposed for the use of positively charged macromolecules, such as polypeptides. Microparticles containing cationic detergents, such as PLG microparticles with CTAB (also known as cetrimide or cetyl trimethyl ammonium bromide), are proposed for the use of negatively charged macromolecules, such as DNA. The use of such microparticles to stimulate immunological responses, including cell-mediated immunological responses, is also disclosed.
In each of the above references, however, one or more surfactants are utilized during preparation of the macromolecule-adsorbed microparticles. Unfortunately, the use of surfactants can raise toxicological issues that result in additional regulatory scrutiny during product registration, among other consequences.